1. Field of the Invention
Embodiments of this invention relate to emergency breathing devices and more particularly relate to backpacks and protective helmets for air extraction from snow.
2. Description of the Related Art
In a typical avalanche accident, the snow accelerates to full speed and the snow mass usually comes to an abrupt halt in the run out zone. The snow packs tightly around the victim and sets up like concrete the instant the moving snow comes to a rest. A buried victim typically finds himself tightly encased in the heavy snow pack. Rarely can a fully buried victim escape this snow encasement by his own efforts.
In addition to being buried and immobilized, the victim's air supply is most often very limited. The victim may or may not have an air pocket in front of his face or surrounding his head. If the head is very near the surface or there is a hole from the head to the surface, the victim is very fortunate. More often than not, however, the facial air pocket is small or nonexistent. As the victim breathes within this small confined space, the oxygen is rapidly consumed and replaced by carbon dioxide. Within a short time, the lack of oxygen and/or the abundance of carbon dioxide may cause asphyxiation and/or suffocation.
Air diffusion, in which air may diffuse through the snow, between the snow pack and the air pocket helps to increase the time of breathable atmosphere. In some cases, air may diffuse from the surface of the snow pack, through the snow, to an air pocket near the victim's face. There is one phenomenon, however, which greatly limits the beneficial air diffusion between the snow pack and air pocket. This phenomenon is known as ice masking. Ice masking occurs when a person exhales warm, moist air into the small air pocket surrounding one's face, where the moisture condenses on the snow surface within the air pocket. After repeated breaths, the layer of moisture builds or thickens, greatly reducing the snow porosity at this boundary due to this accumulation of moisture. Unfortunately, the air within the nearby snow pack may become unavailable to the victim due to this moist snow layer. As a result, the victim rapidly suffocates and, if the victim is not located, unburied, and resuscitated, if necessary, the victim will die. After suffocation, the body temperature drops and the thick moist snow surrounding the face refreezes into what is commonly known as an ice mask. The thickness of this ice mask is a good indication of the length of time the victim remained alive before eventually suffocating.
Many devices have been contrived in an attempt to extend the breathing time of a fully buried avalanche victim. Some of these devices employ carbon dioxide absorbers to absorb and, thereby, reduce the amount of carbon dioxide that is exhaled and rebreathed. Unfortunately, these devices do not address the problems resulting from the limited air that may diffuse through the snow pack. Other devices employ oxygen tanks in order to provide additional oxygen to the victim in addition to or in place of the diffused air. However, these devices are both bulky and heavy and, therefore, inhibit the movement of the user in many of the recreational activities that draw the users to the mountains in the first place. Additionally, many of these devices employ one or more tubes that connect the mouthpiece to the oxygen tank, typically worn on the users chest or back. These tubes may easily be ripped away from the victim's mouth or the oxygen tank due to the forceful movements of the avalanching snow.
Another device, the AVALUNG, which is currently marketed in the United States and elsewhere, also employs a tube to bring air to the victim's mouth. The tube is connected to a type of air pouch that allows air to be drawn in from the surrounding snow pack. Versions of this device are used in jackets or on straps that may be worn as the outermost layer of clothing. In other words, the air pouch may be worn in an exterior compartment of the jacket. Alternatively, the air pouch may be strapped onto the victim via a contraption having a waist strap and a shoulder strap.
However, these pouches are typically located around the victim's stomach or chest area, requiring a long tube to transfer the inhaled air to the user's mouth. As described above, it may be difficult or even impossible to retain the mouthpiece in the user's mouth as the user is tossed about by the avalanching snow. Additionally, an avalanche victim may be swept away by an avalanche before engaging the mouthpiece. This may occur especially where the victim does not see the avalanche begin and/or where the victim does not have an audible warning, for example, due to the noise of heavy equipment or recreational machinery. Additionally, the surface area of the air pouch is typically small and limited by the costs of producing the device and possibly in order to not restrict the user's movement. The device also limits the user's dress because the device must be worn on top of all clothing and apparel worn by the user. The functionality of the device is nullified if it is worn, for example, under a jacket or obstructed by a piece of equipment, such as a backpack.
From the foregoing discussion, it should be apparent that a need exists for an apparatus, system, and method for air extraction from snow that are not subject to the same disadvantages and inconveniences. Beneficially, such an apparatus, system, and method would limit the requirement for long tubes that are likely to be torn away from the victim's mouth. The apparatus, system, and method also would advantageously be incorporated into existing equipment and maximize the amount of surface area used to draw in air diffused through the snow pack.